🎯 Common Question Types:
- Explain the purpose of step-up/step-down transformers in the National Grid [3 marks]
- Calculate output voltage from turns ratio [2-3 marks]
- Calculate output current from power equation [2-3 marks]
- Explain how a transformer works using electromagnetic induction [4 marks]
- Explain why transformers only work with AC [2 marks]
📝 Key Command Words:
- Explain — give the physics reason using equations where relevant
- Calculate — show your working clearly with substitution into formula
- Describe — outline what happens step by step without full explanation
- State — give a brief answer, no explanation needed
- Identify — name or select the correct option from given information
⚠️ Common Mistakes to Avoid:
- Saying transformers reduce resistance — they reduce current, not resistance
- Mixing up which transformer is step-up and which is step-down in the Grid
- Forgetting that transformers only work with AC, not DC
- Not referencing P = I²R when explaining why high voltage reduces power loss
- Confusing the turns ratio: more turns always on the side with higher voltage
This exam tips covers Exam Tips for National Grid and Transformers within National Grid & Transformers for GCSE Physics. Revise National Grid & Transformers in Extra Topics for GCSE Physics with 14 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 11 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Practice questions for National Grid & Transformers
What is the function of a step-up transformer in the National Grid?
Explain why electricity is transmitted at high voltage and low current through the National Grid power cables.
Quick recall flashcards
How does a transformer work?
AC in primary creates changing magnetic field → iron core transfers field to secondary → changing field induces voltage in secondary (electromagnetic induction)
What voltage do homes receive?
230 V